1. Field of the Invention
The present invention relates generally to a semiconductor device, and particularly to a semiconductor device having a bent or curved semiconductor element such as a stacked multi-chip package (MCP) and a multi-chip module (MCM), for example.
2. Description of the Related Art
Presently, attention is being directed to a technique for deforming a flat semiconductor chip into a desired shape for mounting in order to increase integration and operational speed of a semiconductor device. As technology develops for manufacturing a thinner semiconductor chip, it is becoming increasingly easier to deform (bend) the semiconductor chip itself into a desired shape. Japanese Laid-Open Patent Publication No. 2001-118982 and Japanese Laid-Open Patent Publication No. 11-345823 disclose technologies for deforming (bending) and mounting a semiconductor element.
FIG. 1 is a perspective view showing a configuration of a deformed semiconductor chip that is described in Japanese Laid-Open Patent Publication No. 2001-118982. The semiconductor chip 1 shown in this drawing is wrapped around a cylinder-shaped support substrate 2 to be deformed into a cylinder shape. In this drawing, electrode pads 1a of the semiconductor chip 1 are arranged in a longitudinal direction with respect to the cylinder shape and these electrode pads 1a may be used to interconnect to another similar cylindrically deformed semiconductor chip.
FIG. 2 is a side view showing a configuration of a deformed semiconductor chip that is described in Japanese Laid-Open Patent Publication No. 11-345823. One side of the semiconductor chip 3 shown in this drawing has solder bumps 3a mounted thereon as external connection electrodes, and the semiconductor chip 3 is deformed in a manner such this side forms a concave surface. The solder bumps 3a are connected to a wiring portion 4a of an interposer 4. According to this configuration, even when the interposer 4 is thermally deformed, stress created between the semiconductor chip 3 and the interposer 4 (i.e, at the solder bumps 3a) may be alleviated since the semiconductor chip may easily deform (bend).
However, in the example of FIG. 1, the semiconductor chip 1 is wrapped around a cylindrical substrate 2, and thereby, the weight of the semiconductor device may increase. Also, depending on the connection state of the chips (e.g., when the chips wrapped around a cylinder structure are mounted on top of each other), the chips that are to be mounted may need to be interconnected, and thereby the pads of the chips may have to be adjusted. Consequently, redesigning of the chip structure may be required, and the conventional semiconductor chip may not be used in its present form. Also, the semiconductor chip 1 has to be precisely wrapped around the cylinder substrate 2, and in turn measures for realizing such effect need to be contemplated.
Also, when a semiconductor chip is deformed and flip chip mounted as in the case of semiconductor chip 3 of FIG. 2, the chip is thin and lacks strength so that a crack may be generated upon connecting the chip to the interposer or sealing the structure with resin, for example. Further, since the semiconductor chip is deformed into an arc shape, the positioning accuracy of the connection portion between the interposer and the semiconductor chip may be low.